DNA legacy of ancient seafarers

[Jonna Herring]

DNA legacy of ancient seafarers
By Paul Rincon
Science reporter, BBC News




Phoenician written text on a stone (AFP/Getty)
The Phoenicians took their alphabet with them on their travels

Scientists have used DNA to re-trace the migrations of a sea-faring civilisation which dominated the Mediterranean thousands of years ago.

The Phoenicians were an enterprising maritime people from the territory of modern-day Lebanon.

They established a trading empire throughout the Mediterranean Sea in the first millennium BC.

A new study by an international team has now revealed the genetic legacy they imparted to modern populations.

The researchers estimate that as many as one in 17 men from the Mediterranean may have Phoenician ancestry.

   
When we started, we knew nothing about the genetics of the Phoenicians
Chris Tyler-Smith
Wellcome Trust Sanger Institute
They employed a new analytical technique to detect the subtle genetic imprint of historical migrations in present-day people. The study included DNA data from more than 6,000 men from around the Mediterranean.

From their base in present-day Lebanon, the Phoenicians spread out across the sea, founding colonies and trading posts as far afield as Spain and North Africa, where their most powerful city - Carthage - was located.

Carthage spawned the audacious military commander Hannibal, who marched an army over the Alps to challenge the Roman Republic on its own territory.

The Phoenicians have been described as the world's first "global capitalists". They controlled trade throughout the Mediterranean basin for nearly 1,000 years until finally being conquered by the Romans.

Over subsequent centuries, much of what was known about these enigmatic people was lost or destroyed.

[Jonna Herring]

Digging deep

"People have not really looked at this heritage, and I think we ought to be looking more," Dr Pierre Zalloua, from the Lebanese American University in Beirut, Lebanon, told BBC News.

Chris Tyler-Smith, co-author of the paper from the Wellcome Trust Sanger Institute in Cambridge, UK, commented: "When we started, we knew nothing about the genetics of the Phoenicians. All we had to guide us was history.


Archaeologists excavating Phoenician settlement in Beirut, Lebanon
The researchers used historical information to focus their study
"We knew where they had and hadn't settled. But this simple information turned out to be enough, with the help of modern genetics, to trace a vanished people."

The new findings have emerged from the Genographic Project, a multi-million-dollar effort to trace human migrations using genetics. Details appear in the prestigious American Journal of Human Genetics.

The study focused on the Y, or male, chromosome, a package of genetic material carried only by men that is passed down from father to son more or less unchanged, just like a surname.

But over many generations, the chromosome accumulates small changes, or copying errors, in its DNA sequence.

These can be used to classify male chromosomes into different groups (called haplogroups) which, to some extent, reflect a person's geographical ancestry.

They looked at the genetic signatures carried on the Y chromosomes of men from former Phoenician colonies across the Mediterranean. The sites included coastal Lebanon, Cyprus, Crete, Malta, eastern Sicily, southern Sardinia, Ibiza, southern Spain, coastal Tunisia and the city of Tingris in Morocco.

They then compared the Y chromosomes of these men with those of males from nearby places where the Phoenicians had never lived.

This focussed approach uncovered a small number of recurring genetic signatures in men from the Phoenician sites. These genetic lineages also led back to the Levant region - the Phoenician homeland.

[Jonna Herring]

Genetic 'jacuzzi'

But several human migrations - both historic and prehistoric - have started in the Eastern Mediterranean and spread out to Europe and North Africa.

These include the migrations of early farmers from the Near East after 10,000BC, the expansion of the ancient Greeks who - like the Phoenicians - established outposts around the Mediterranean, and the Jewish diaspora.

Because of their geographical proximity, the people involved in these expansions may have carried similar genetic signatures to the Phoenicians.

   
Teasing apart something that's specifically Levantine, or Phoenician, from the background of the general Neolithic expansion, or Greek colonisation, is actually quite tough
Spencer Wells
Genographic Project director

However, the team devised special analytical methods which they say can distinguish the Phoenician input from other possibilities.

"The issue here is that the Mediterranean is a genetic jacuzzi, if you will, it's had people moving around all over the place for millennia," said Spencer Wells, director of the Genographic Project.

"Teasing apart something that's specifically Levantine, or Phoenician, from the background of the general Neolithic expansion, or Greek colonisation, is actually quite tough.

"That's why we needed this formalised approach and obviously the (large) sample sizes to detect this signal."

This strategy revealed six candidate "Phoenician" lineages. Overall, these made up 6% of genetic lineages found in modern populations from former Phoenician colonies around the Mediterranean.

That means one in 17 men from these sites could trace their male ancestry to a Phoenician, the researchers said.

Co-author Daniel Platt, from IBM's Computational Biology Center at the TJ Watson Research Center, said the study "proves that these settlements, some of which lasted hundreds of years, left a genetic legacy that persists to modern times".

Dr Wells explained that the technique used in this study could be applied to track other migrations which had subtle genetic impacts.

He cited the expansion of Celtic-speaking people from their homeland in the Harz mountains of Germany into Western and Eastern Europe during the first millennium BC.

The Genographic Project was launched in 2005, and involves National Geographic, IBM, the Waitt Family Foundation and Applied Biosystems.

Paul.Rincon-INTERNET@bbc.co.uk

http://news.bbc.co.uk/2/hi/science/nature/7700356.stm